The need to cut cables underwater is of great importance to marine engineering. With the expansion of moored systems, e.g., data buoys to underwater anchors, methods at cutting the cables attaching such systems to the anchors have become of great interest. Devices have been designed and constructed of all types for the purpose of cutting these cables.
Mechanically, most cable cutters utilize an anvil and cutter combination powered by some means to cause the cutter to sever a cable by impinging it against the anvil. Many prior systems have been entirely mechanical in operation. Later systems have introduced explosive methods of actuating the cutter against the anvil. Such actuation is initiated by mechanical means at the time the cutter is attached to the cable to be cut, or by some form of a time delay. Various forms of time delays have included trip wires, electrical detonation wires, as well as through delayed mechanical contact with the cable to be cut.
The utility of a cable cutter which is remotely actuated depends on several factors. One factor is the requirement to activate the cutter from a remote position for purposes of safety. A second factor is the desire to activate the cutter remotely at a preselected chosen time.
A particular desire for remotely controlled cable cutting is to have the ability to activate several separate cable cutters according to a preplanned sequence in a manner that firing of one cutter does not interfere with the firing of any other cutter. This capability leads to a very valuable method of planning the cutting of multiple cables through remote commands as part of a time sequence of events. Such a requirement occurs where large items tethered by several cables are to be cut such that the items released will either float to the surface in a predetermined orientation, or vice verse, are to be cut from a surface vehicle to float and settle on the bottom in a predetermined orientation.